/Engine/Plugins/Online/OnlineFramework/Source/Lobby/Public/LobbyBeaconState.h
Delegate fired when the player state in the lobby has changed (add/remove/etc)
typedef TMulticastDelegate_OneParam< void, [ALobbyBeaconPlayerState](API\Plugins\Lobby\ALobbyBeaconPlayerState) * > FOnPlayerLobbyStateChanged